Fix voice camera tilt from a top-down view

A voice fly-to frames a city top-down, at pitch -90. The tilt clamp
rejected any step that left the pitch below -89, so the first frame of
"tilt up" stopped the motion and "tilt down" was refused: from the view
voice lands on, no tilt ever moved the camera. A bare "tilt the camera"
also failed because tilt required a direction.

- Clamp tilt only in the direction of travel, so -90 can tilt up.
- Swing the camera about the ground under the crosshair, so the place
  stays centred and the heading is kept. A tracked view still tilts in
  place, and a pivot tilt yields when tracking takes the camera.
- Add an optional move_camera pitchDeg for "tilt 45 degrees"; a tilt
  with neither angle nor direction settles at -45 (oblique view).
- Re-derive the voice tool schema pins for the new argument and wording,
  and keep the Realtime prompt under its 52,000-character budget.

server/providers/openai/toolDescriptions.js

@@ -523,7 +523,7 @@ export const ACTION_DESCRIPTIONS = {
       properties: {
         direction: {
           description:
-            'Required for pan/tilt/rotate; orbit/rotate_globe default right.',
+            'Required for pan/rotate and a tilt nudge; orbit/rotate_globe default right.',
           $position: 2,
         },
         mode: {
@@ -531,6 +531,11 @@ export const ACTION_DESCRIPTIONS = {
             'once = bounded eased nudge; continuous = until stop/manual input. rotate_globe defaults continuous; other motions default once.',
           $position: 2,
         },
+        pitchDeg: {
+          description:
+            'Tilt to this angle below the horizon (-45 oblique, -89 top-down). Bare tilt: -45.',
+          $position: 2,
+        },
       },
     },
   },